1 Electric HP = 2 ICE HP?

Can someone explain this to me?

Is it to imply that an electric has two times the acceleration per horsepower(Generally very roughly speaking of course) or that a car literally provides two times the amount of output power than an ICE per rated HP? If so, than what does an ICE HP stand for? Is it something like "the total amount of power the gasoline provides, including the portion that goes to heat the engine and create that wonderful combustion noise"?

1 horsepower = 750 watts. It doesn't mater where that comes from.

But an electric motor makes much better torque than the equivilent watt or horsepower output gas motor.
its a little like comparing Diesel to gas. You could have a truck with a 350hp V8 gas, or a 160 horsepower diesel. Which would pull a 18,000 boat better?

its sort of apples and oranges unless you are specificly comparing something.

IMHO, 1 orange=2 apples

It is because ICE is measured in Max (Peak) HP and electric motors are measured in Max Continious Power. An electric motor can make up to 4 times it's continious power rating in short bursts.

Generally speaking ICE are rarely used at peak power.

drewjet said:

It is because ICE is measured in Max (Peak) HP

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Is that true? I feel so deceived now. So those "12 Hp" 50cc bikes are probably what continuous? 5 Hp?

In english units, hp is..... ft*lbf/s.

If a motor is producing a set value of torque at low rpm, the hp is different than an engine delivering the same torque at a higher rpm.

Here is an example of torque hp curves on a honda engine.



The peak torque and peak power do not occur in the same rpm range. The peak power occurs when the max amount of torque per second is delivered which is a function of rpm.

....so, if an electric motor delivers more torque at low rpm, its power rating will be different from an ICE engine delivering its peak torque at higher rpm. Even if the torque value is the same for both.

gasoline engines have a horsepower "bell curve", and you know how manufacturers are...they advertise PEAK HP.

Gasoline engines really dont have a continuous RPM/load "setting" and then a peak temporary load. Motors are like that. You normally buy the smallest cheapest e-motor that can do the job at a continuous RPM at a specific voltage. That being said we can all overvolt motors a little as long as we dont over-load them too much or for too long a time, then they gain more heat than they can shed.

An electric motor has better efficiency at higher RPM's, but as far as power goes, they have most of it available from a standing start. If you can vary armature current (as some are experimenting with) you can use only the current needed. More at the start, and less as speed increases and stabilises. The simplest common motors dont vary armature current, so they get hot under heavy loads such as standing start accelleration, and then they are wasteful of Watts when just cruising.

If motors were dirt cheap and batteries were horribly expensive, there would be more creativity with motors. Fortunately the selection is improving for everyone recently. I'm no expert, but I've read of some of the ways to have max design accelleration power and also "watt-sipping" cruise are: two free-wheeling motors. Both used for accel, and one used for cruise, then, motor/voltage selected for max loads, but armature current is adjustable to only whats needed at that moment, also, Delta/Wye switching, also sacrificing raw accelleration and hill-climbing speed by using a smaller motor, but running it through a 3-speed trike hub as a transmission.

Another idea with the wide RPM range available with the recent RC motor experiments might be voltage switching. Perhaps 48V for acceleration, then 24V for range? (don't know if that would work or not...)

My 18-wheeler only has about 500 HP, but I have 14 gears and accellerate slowly, so I get 7 MPG when hauling 80,000 lbs. (40 tons) Can you imagine a 100 HP economy car hauling 16,000 lbs (8 tons)

drewjet said:

It is because ICE is measured in Max (Peak) HP and electric motors are measured in Max Continious Power. An electric motor can make up to 4 times it's continious power rating in short bursts.

Generally speaking ICE are rarely used at peak power.

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According to everyone else, "peak power" is the top of that typical power curve. However, if that was the case, than it would be possible to gear the motor so that the RPM of the motor coincided with its peak power. Can that peak power be run continuously without risking the engine going blown or is that rarely done?

In my opinion, it seems there HAS to be a limit of some sort to gasoline engines. Is there really no limit within the range of its operation and it can get as hot as it wants so it can thus be operated as its "peak power" continuously if so chosen? This is opposed to electric motors which can overheat by exceeding a given current rating for a specific amount of time.

Drunkskunk said:

IMHO, 1 orange=2 apples

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and 1 banana > (1 orange + 2 apples)

swbluto said:

According to everyone else, "peak power" is the top of that typical power curve. However, if that was the case, than it would be possible to gear the motor so that the RPM of the motor coincided with its peak power. Can that peak power be run continuously without risking the engine going blown or is that rarely done?

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Yeah, they can run at peak for as long as you want assuming something doesn't go horribly wrong with the cooling system. They probably won't last as many miles as running it at a lower power, but it's not like a motor that can be burnt up almost instantly if you give it too much juice.

swbluto said:

In my opinion, it seems there HAS to be a limit of some sort to gasoline engines. Is there really no limit within the range of its operation and it can get as hot as it wants so it can thus be operated as its "peak power" continuously if so chosen? This is opposed to electric motors which can overheat by exceeding a given current rating for a specific amount of time.

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Until you get into riduculous modifications like they do in F1 cars where the engine won't last for more than a few races, mostly how much gas you can burn. Turbos, superchargers, race cooling systems, etc. are all for getting as much gasoline/air mixture as possible into the cylinder per stroke.

The reason an electric does so much better is because motors are not rated the same as engines. Since a motor is only rated by what it can produce continuously and a gas is rated what it can make at its maximum power output, the motor can, in actuality, do more than the engine.

The reason an electric does so much better when their maximum power outputs are really equal in max power is because the torque curve of a motor is ideal for getting moving from a stop: Low RPM when high torque is needed, which tapers off into its powerband, which eventually tapers off into its efficiency band (which is basically the exact opposite of an engine, IIRC).

This is coming from a guy who's only experience with a real gas engine is quadding twice in his life. So, uh...yeah.